1. Field of the Invention
This invention relates to optical systems and, more particularly, to reducing contamination in optical devices.
2. Description of the Related Art
Many optical devices include mirrors, lenses, and other optic components that are used to process light. These optical components are often very sensitive to contamination. The presence of contaminants on the optic components may decrease the performance of an optical device. For example, the presence of contaminants may lead to an increase in a device's insertion loss. Insertion loss is total optical power loss caused by the insertion of an optical device into a system. The cleanliness of the optics may also affect signal to noise ratio and return loss.
One example of contamination occurs in high power optical systems. In these systems, dirt on the surface of an optical component may act as a tiny lens that locally focuses a light beam until the intensity burns a hole in the surface of that component (or a coating on that component), increasing the insertion loss of that component.
In order to reduce the possibility of contamination, great care is usually taken when handling optic components. Optical components are typically enclosed within sealed packages to prevent environmental contaminants such as dirt and water from coming into contact with the enclosed optical components. However, various processes used during the assembly process of optical devices may themselves create contaminants. For example, soldering, epoxy bonding, and laser welding may each produce contaminants through outgassing, smoking, and/or splashing (e.g., of flux). This contamination results in what is commonly referred to as “fogging” on the optics. Like other forms of contamination, this fogging may cause insertion loss or otherwise reduce performance.